The season pass for Injustice: Gods Among Us gives us access to four new fighters (Lobo, Batgirl, Scorpion and the last remains unannounced... although the accurate leak points to General Zod), and now NetherRealm Studios' creative director Ed Boon has confirmed they aren't done with DLC characters after that! Boon is well-known for teasing on Twitter, but this is a clear and direct official announcement: there's at least one more DLC character on the way. The best news of all? He claims this combatant "came from player requests."
If the leak holds up and the fourth DLC character is General Zod, then I have to assume this fifth character is Martian Manhunter. There's been so much demand for the character and he was even teased at the end of Scorpion's trailer. The character select screen absolutely has room for at least three more characters after the fifth addition, so here's hoping they offer a second season pass (which would hopefully include a good skin pack, of course). Additionally, Boon stated the fourth character will be revealed next week.